Extreme episodes and long-term trends – evidence at a groundwater tributary to a humic lake

During the past 150 years, the northem Black Forest region in Germany has been severely impacted by air pollution and acidic precipitation. Studies at small dystrophic cirque lakes in this area ( e.g. at Lake Huzenbach; ARZET 1987, HILGERS et al. 1993, S TEINBERO & HóGEL 1990, THIES 1994, l995a, l995b, 1997, 2000) revealed related environmental impacts from a limnological perspective. Until the late l990s, air pollution abatement measures had reduced sulphur emissions in Germany by about 90% with respect to 1980 levels (UBA 2003). An automatic data acquisition has been installed at a groundwater tributary to Lake Huzenbach to study long-term trends and extreme episodes at high temporal resolution with robust sensors.